ML19290E703
| ML19290E703 | |
| Person / Time | |
|---|---|
| Site: | Perkins, Cherokee  |
| Issue date: | 03/07/1980 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Dail L DUKE POWER CO. |
| References | |
| NUDOCS 8003140409 | |
| Download: ML19290E703 (2) | |
Text
'o UNITED STATES 8
~,,
g(
g NUCLEAR REGULATORY COMMISSION r
REGION 11 0,
101 MARIETTA ST,, N.W., SUITE 3100 ATLANTA, G EORGIA 303o3 M 071980
[
In Reply Refer To:
RII:JPO 50-491, 50-492 50-493,CTO TB8:
g 3
c50-589,310-7.901-p Duke Power Company Attn:
L. C. Dail, Vice President Design Engineering P. O. Box 33189 Charlotte, NC 28242 Centlemen:
This Information Notice is provided as an early notif. ation of a possible significant matter.
It is expected that recipients will distribute this Notice to their operating personnel and will review the information for possible applic-ability to their facilities. No specific response is requested at this time.
However, we anticipate that further h7C evaluations will result in issuance of an Addendum to IE Bulletin 79-27 in the near future which will recommend or request specific applicant or licensee actions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely
\\
@l - '
t mes P. O'Reilly D ector
Enclosures:
1.
IE Information Notice No. 80-10 w/its Enclosure 2.
List of IE Information Notices Recently Issued 8003140 OCf
MAR 0 71980 Duke Power Company.
cc w/ enc 1:
J. T. Moore, Project Manager Post Office Box 422 Gaffney, South Carolina 29340 d
0
SSINS No.:
6870 UNITED STATES Accet; ion No.:
NUCLE AR REGULATORY COMMISSION 8002280640 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 7, 1980 IE Information Notice No. 80-10 PARTIAL LOSS OF NON-NUCLEAR INSTRUMENT SYSTEM POWER SUPPLY DURING OPERATION Description of Circumstances:
This notice contains information regarding Crystal River Unit 3 response to a loss of non-nuclear instrumentation (NNI) as a consequence of loss of the
+24 volt power supply to the NNI.
At 2:23 p.m. on February 26 with Crystal River Unit 3 at 100% power, the
+24 volt power supply to the NNI was lost, due to a short to ground. This initiated a sequence of events (detailed in the enclosure) wherein the PORV opened and stayed open as a direct result of the NNI power supply loss.
HPI initiated as a result of depressurization through the open PORV, and with approximately 70% of NNI inoperable or inaccurate, the operator correctly decided that there was insufficient information available to justify terminating HPI. Therefore, the pressurizer was pumped solid, one safety valve lifted, and flow through the safety valve was sufficient to rupture the RC Drain Tank rupture disk, spilling approximately forty-three thousand gallons of primary water into containment.
The Crystal River 3 event is clo'sely related to the November 10, 1979 event at Oconee Unit 3 wherein the inverter supplying power to the Integrated Control System (ICS) and to parts of the NNI failed. That event was the subject of IE Information Notice 79-29 (November 16, 1979) which was followed by IE Bulletin 79-27 (November 30, 1979).
The CR-3 event involved loss of only part of the power avoilable from an inverter, rather than the inverter itself, since the +24v supply is only one of several power supplies drawing power from one inverter. The effects are very similar, however, in that the ICS lost part of its input signals in both events.
The +24 volt power supply short to ground has tentatively been identified by the licensee to have occurred between knife edge connectors of a Bailey Control Company Voltage Buffer Card. The voltage buffer card was misaligned in its receptacle, and adjacent connectors car
+
that they contacted one another. Th subsequent re-energizing of the powe printed circuit card. Subsequent re DUPLICATE DOCUFUCNT voltage buffer card which was also m The specific circuit cards which wer Entire document previously The connectors on these cards are sl entered into system under:
different angle than those found on ANO carry part numbers 6624608A1 or 66246,,_
more subject to misalignment.
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